FIG 2. Case 8: 48-year-old woman with history of vasculitis and chronic renal failure who presented with seizures.

A, Initial MR study, FLAIR sequence, reveals typical subcortical edema of PRES in the left posterior frontal lobe (arrow). This patient also had mild cortical involvement of the parietooccipital regions, the left posterior temporal lobe, and the left thalamus. These findings were assigned a severity ranking of 2 (moderate disease).

B, Follow-up FLAIR image 5 days after original presentation. Although the left posterior frontal subcortical edema has resolved, there was an overall progression of the findings of PRES with new right posterior frontal cortical hyperintensity (arrows).

C, FLAIR image, at same level, 7 days after original presentation, shows mild worsening of edema, now bifrontal, with some new subcortical foci (arrowheads).

D, T2-weighted image shows new bilateral cerebellar hyperintense foci (arrows).

E, Cerebellar lesions are seen better on FLAIR image (arrows). This patient has parietooccipital lesions typical of severe PRES. Extension of edema to involve the cerebellum bilaterally was considered to warrant a severity index of 3 (severe disease).